As people pursue a comfort life, an interest for a location-detecting technology for detecting a location of a user in a real time increases. Usually, a user have at least one mobile terminal and the detecting a location of the user can be performed through the mobile terminal.
Detecting a location of a mobile terminal may be performed through a GPS (Global Location System), a location service provided by a mobile-service company, and RFID (Radio Frequency Identification) or IR/Ultrasonic wave. According to the location detecting technology through GPS, GPS signal is received by an antenna of a mobile terminal, and a location of a user can be calculated based on the GPS signal and displayed on a display of the mobile terminal. According to the location detecting technology through the location service provided by a mobile-service company, a base station connected with a user (who joins the location service provided by a mobile-service company) is determined, and information that the user is within the service area of the base station is provided to the user. According to the location detecting technology through the RFID or the IR/Ultrasonic wave, the location of a user is measured by a wireless signal or IR/Ultrasonic wave provided at least three access points (APs).
However, the location detecting technology through GPS cannot be used in an area where the GPS signal cannot arrive (for example, an indoor area or an area with concentrated buildings). Moreover, the location detecting technology through the location service provided by a mobile-service company cannot focus the location of a user within a range of a few meters since the service area of the base station is very broad (hundreds of meters˜a few kilometers). Further, the location detecting technology through RFID is not effective in expenses since a lot of RFID readers should be equipped in location detecting area, and the location detecting technology through IR/Ultrasonic wave cannot be used under non-catchable environment. Therefore, it is hard to use the location detecting technology through IR/Ultrasonic wave in a general office.
On the other hand, as VLC (Visible Light Communication) technology, which transmits data through visible light (400˜700 nm), develops, interest in technology of location a user (or the mobile terminal) by using visible light increases.
However, until now, the technology is confined only in a communication based on indoor lighting apparatus, so that advanced location-based service is limited. Therefore, there exists a need for transmitting and receiving function with a mobile smart device anywhere and at any time, and a development of a system capable of embodying precise LBS is requested.